This paper analyses, from the point of view of compared cartography, some maps of the Amazon region from the mid-eighteenth century, having as central axis the Carte de l'Amérique Meridionale produced in 1748 byBourguignon D'Anville, a French cartographer who has worked closely with the Portuguese ambassador Don Luis da Cunha, in order to produce a map that would serve as a basis for the ongoing negotiations of the Madrid's Treaty. In addition to collate it with a current map, to observe concordances and dissonances, two other comparisons are made: one with the resulting map of La Condamine's expedition, drawn by D'Anville (1744), and the other with the so-called Mapa das Cortes, produced in Lisbon under the auspices of Alexandre de Gusmão, which was the map effectively used to support the negotiations of this Treaty of 1750 that made the division of South America. This methodology combines an European diplomatic policy analysis with the tracing of cartographic sources that, in turn, is confirmed by the digital cartography, involving studies of map accuracy and statistical analyses. This combination of methods proved to be a powerful tool for the analysis of cartographic production, understood in its broadest sense and opens new frontiers of work and research.